Resin packaging bag for microwave oven, method for heating same, method for filling resin packaging bag for microwave oven, and package

ABSTRACT

A resin packaging bag for a microwave oven, which is used with a peripheral edge portion sealed, characterized in that: a front side of the packaging bag is formed from one resin film  2  and a rear side is formed from one resin sheet  1 ; and the resin film and the resin sheet comprise materials that, when a packaged body obtained by hermetically sealing moisture-containing contents between the resin film  2  and the resin sheet  1  is heated in a microwave oven with the rear side resin sheet as a bottom surface, are deformed by heat and pressure of steam generated from the contents such that the rear side resin sheet forms a recessed shape, and the recessed shape is entirely or partially maintained even after heating is terminated.

TECHNICAL FIELD

The present invention relates to a packaging bag for packaging food andthe like.

BACKGROUND ART

A microwave oven has become a widespread fixture in households as aninstrument for both heating and cooking food in addition to conventionalcooking utensils for heating and cooking food, such as pots and fryingpans.

Hence, with advancements in heat sterilization and refrigerationtechnology, it has become common simply to heat packaged pre-cooked orsemi-cooked retort food, frozen food, and refrigerated (chilled) food ina microwave oven or the like and eat the food as is (see Patent Document1).

Moreover, households consisting of two members or less have shown anincreasing tendency recently, leading to an increase in the need forfood prepared for one to two people. In particular, as the baby-boomergeneration retires and the number of elderly people increases, thenumber of households in which meals are prepared at home is increasing.These changes in social conditions have been reflected in conveniencestores by rapidly increasing the assortment of individual portions ofrefrigerated (chilled) prepared side dishes, and in particularincreasing the assortment of bagged food. In addition to theserefrigerated (chilled) side dishes, the assortment of available frozenfood such as fried dumpling and pasta or the like that is topped withsauce and then frozen as is has also increased. All of these productsare eaten after being heated in a microwave oven either in-store or athome.

Incidentally, retort food and frozen food is typically assumed to have along shelf life, and is not intended to be cooked or sold in a shortperiod of time.

The following three methods are employed as methods of distributingcommercially prepared moist processed food to stores.

(1) Distribution at room temperature (the food is distributed and soldat room temperature after undergoing aseptic filling processing orretort sterilization processing).

(2) Distribution in a refrigerated state (the food is distributed andsold at 3 to 10° C. after undergoing aseptic filling processing or heatsterilization processing).

(3) Distribution in a frozen state (the food is frozen and thendistributed and sold in a frozen state).

In all of the distribution methods described in (1) to (3), the food ispackaged in a bag, a plastic container, a can, or the like. In the caseof methods (1) and (2) in particular, the packaged food is typicallyvacuum-packed and then subjected to heat sterilization processing beforebeing shipped and displayed either at room temperature or in a chilledstate in order to extend the best-before date of the food.

Aseptically filled packaged products obtained by sterilizing a liquidsuch as a beverage in a large quantity in advance using a plate typesterilization device, filling a sterilized container with the liquid ina sterile environment, and then hermetically sealing the container aredistributed at room temperature, but moist processed food, includingsolids, cannot easily be processed using this method.

For processed side dishes and fish and meat products, a method ofhermetically sealing the product in a bag or a plastic container andthen killing bacteria in the food by retort sterilization processing, amethod of implementing heat sterilization processing on the product tokeep the amount of bacteria in the food at or below a fixed bacteriacount and then storing, distributing, and selling the product at a lowtemperature to prevent the bacteria from proliferating thereafter, or amethod of freezing the food immediately after cooking and thendistributing and selling the food in a frozen condition is generallyemployed.

When retort sterilization processing or heat sterilization processing isperformed in a condition where headspace (an air gap) exists in the bagor the container, the sterilization time increases greatly due to anadiabatic effect of the air, leading to alteration in the texture(firmness, tongue feel, throat feel, and so on), taste, color, and smellof the food contents. Moreover, when heat sterilization is performedusing steam or hot water under ordinary pressure, the bag or containerruptures due to thermal expansion of the air.

Frozen pasta and the like packaged in a container sealed by a fitted lidis not sealed completely hermetically and is not therefore suitable forlong-term frozen storage. Regarding frozen food, when food is frozen,the surface area of the food increases, and therefore oil in the food islikely to be oxidized by oxygen in the container even in a lowtemperature environment. To maintain a nitrogen environment in thecontainer by enclosing a deoxidant therein, a flange part of a containermain body must be hermetically sealed using a laminated film lid so thatthe interior of the container is completely cut off from outside air.

To heat pasta or the like packaged in a container in a microwave oven, apart of the lid film must be peeled away in advance to let the steamgenerated during heating escape. An increase in internal pressure isrequired during heating in a microwave oven to maintain theenvironmental temperature in the container at approximately 100° C., andthis is particularly desirable to shorten the time required to defrostand cook frozen food.

However, in addition to the limitation on the heating effect caused bythe existence of the headspace, when a part of the lid film is peeledaway in advance, the interior of the container cannot be maintainedabove ordinary pressure, and therefore the cooking time naturallyincreases.

Further, when a packaging container combining a molded container and alid member and including headspace is used as a packaging material, anouter shape of the molded container collapses during vacuum-packing.

Moreover, when retort sterilization processing is implemented on apackaging container, an internal pressure of a retort device must becontrolled such as to be adjusted in response to raising/lowering in thetemperature of the food product in the container to prevent thecontainer from deforming. Negative effects are also received from theadiabatic effect of the air, as described above.

As described above, a packaging container is not suitable for a case inwhich sterilization processing is performed after vacuum-packing.

Therefore, a packaging bag formed from a heat-resistant plastic film isusually employed as a packaging material. The packaging bag is filledwith the side dish or the meat or fish product and then vacuum-sealed sothat air is completely eliminated from the interior thereof, and in thiscondition retort sterilization processing or sterilization processingusing steam or hot water is performed.

To cook packaged food packaged in a packaging bag using a microwaveoven, the purchaser typically transfers the food from the bag to avessel and then heats the food.

Incidentally, the bag expands due to steam generated during heating, andtherefore the bag is typically either partially opened prior to beingheated in the microwave oven, or heated while the steam escapes throughexhaust vents provided in the bag as a function for making the bagusable in a microwave oven, until heating is finished.

However, scalding may occur when the bag is removed from the microwaveoven, and in order to eat the food as is it is necessary to transfer thefood to another vessel. Similar difficulties arise even when the food istaken home.

Transferring the food to a vessel is laborious, and the vessel must bewashed after use. Furthermore, when the vessel is disposable, the amountof garbage increases.

PRIOR ART DOCUMENT

Patent Documents

Patent Document 1: Japanese Patent Application Publication No.2008-290738

SUMMARY OF THE INVENTION Problems that the Invention is to Solve

An object of the present invention is to provide a novel resin packagingbag (resin-made packaging bag) with which heat sterilization can beimplemented after vacuum-packing, the contents of the bag can be cookedin a microwave oven as is without being transferred to a vessel, and thepackaging material itself can be used as a vessel.

Means for Solving the Problems

The present inventors etc. arrived at the present invention with thediscovery that when one surface of a packaging bag to be used with aperipheral edge portion sealed is formed from a resin sheet and anothersurface is formed from a resin film, whereupon moisture-containingcontents are housed in the packaging bag and the bag is subjected tomicrowave heating in a microwave oven with the resin sheet side as abottom surface, heat and pressure from steam generated from the contentsact to increase an internal volume of the packaging bag such that theresin film expands, thereby pulling up the peripheral edge portion ofthe resin sheet with the result that the resin sheet deforms into avessel shape, and the resin sheet remains in this deformed shape stateeven after heating is finished.

To achieve the object described above, the present invention isconfigured as follows.

(1) A resin packaging bag for a microwave oven, which is used with aperipheral edge portion sealed, characterized in that: a front side ofthe packaging bag is formed from one resin film and a rear side isformed from one resin sheet; and the resin film and the resin sheetcomprise materials that, when a packaged body obtained by hermeticallysealing moisture-containing contents between the resin film and theresin sheet is heated in a microwave oven with the rear side resin sheetas a bottom surface, are deformed by heat and pressure of steamgenerated from the contents such that the rear side resin sheet forms arecessed shape, and the recessed shape is entirely or partiallymaintained even after heating is terminated.

(2) The resin packaging bag for a microwave oven described in (1),characterized in that the resin sheet is a resin laminated sheetobtained by adhering a resin film to a rear side surface thereof.

(3) A resin packaging bag for a microwave oven, which is used with aperipheral edge portion sealed, characterized in that: a front side ofthe packaging bag is formed from two resin films and a rear side isformed from one resin sheet; of the two resin films, a resin sheet-sideresin film is adhered to a front side surface of the resin sheet; andthe resin films and the resin sheet comprise materials that, when apackaged body obtained by hermetically sealing moisture-containingcontents between the two resin films is heated in a microwave oven withthe rear side resin sheet as a bottom surface, are deformed by heat andpressure of steam generated from the contents such that the rear sideresin sheet forms a recessed shape, and the recessed shape is entirelyor partially maintained even after heating is terminated.

(4) The resin packaging bag for a microwave oven described in (3),characterized in that the resin sheet and the resin sheet-side resinfilm are adhered weakly and the adhesive layer is weakly adhesive sothat when the packaging body is heated in the microwave oven, the resinfilms housing the contents can be separated from the resin sheet.

(5) A resin packaging bag for a microwave oven, which is used with aperipheral edge portion sealed, characterized in that: a front sideresin film and a rear side resin film are overlaid onto respective sidesof a resin sheet; the resin film and the resin sheet comprise materialsthat, when a packaged body obtained by hermetically sealingmoisture-containing contents between the front side resin film and theresin sheet is heated in a microwave oven with the rear side resin filmas a bottom surface, are deformed by heat and pressure of steamgenerated from the contents such that the rear side resin sheet forms arecessed shape, and this recessed shape is entirely or partiallymaintained even after heating is terminated.

(6) The resin packaging bag for a microwave oven described in (5),characterized in that the front side resin film and the rear side resinfilm are formed by forming a back lining seal on one resin film.

(7) The resin packaging bag for a microwave oven described in any of (1)to (4), characterized in that the resin packaging bag for a microwaveoven is formed by disposing moisture-containing contents between anelongated resin sheet, or an elongated resin sheet having a resin filmadhered to a surface thereof that is to form an inner side of thepackaging bag, and an elongated resin film, forming a four-way seal foreach unit region in which the contents are disposed, and cutting outindividual pieces using a cutter.

(8) The resin packaging bag for a microwave oven described in any of (1)to (7), characterized in that a slit is inserted into the resin sheet.

(9) The resin packaging bag for a microwave oven described in any of (1)to (7), characterized in that a shallow recessed portion is formed inadvance near a central portion of the resin sheet.

(10) The resin packaging bag for a microwave oven described in any of(1) to (7), characterized in that respective pluralities of annularrecessed portions and annular projecting portions are formedconcentrically and alternately in advance in the resin sheet.

(11) The resin packaging bag for a microwave oven described in any of(1) to (10), characterized in that a gore is provided on the resin film.

(12) The resin packaging bag for a microwave oven described in any of(1) to (11), characterized in that means by which a steam vent opensautomatically while heating in the microwave oven is provided on thesurface of the resin film.

(13) The resin packaging bag for a microwave oven described in any of(1) to (11), characterized in that a part of a seal portion between theresin film and the resin sheet is formed from a weak seal so that theweak seal part peels away during heating in the microwave oven, therebyopening as a steam vent.

(14) A method for heating a resin packaging bag for a microwave oven ina microwave oven, characterized in that the resin packaging bag for amicrowave oven described in any of (1) to (13) is heated in themicrowave oven in a condition where all or a part of the peripheral edgeportion of the resin packaging bag for a microwave oven is sandwiched bya frame so that, when the packaging bag undergoes plastic deformationwhile being heated in the microwave oven, a flange part of the resinsheet remains substantially horizontal.

(15) A method for heating a resin packaging bag for a microwave oven ina microwave oven, chracterized in that the resin packaging bag for amicrowave oven described in any of (1) to (13) is heated in themicrowave oven in a condition where all or a part of the peripheral edgeportion of the resin packaging bag for a microwave oven is sandwiched bya frame that includes, on the resin sheet side of the resin packagingbag for a microwave oven, a wall surface that controls plasticdeformation of the packaging bag during heating in the microwave oven.

(16) A bag feeding type automatic filling method, characterized bycomprising filling the resin packaging bag for a microwave ovendescribed in any of (1) to (13), which is sealed at three sides, withmoisture-containing contents through an opening portion of the resinpackaging bag for a microwave oven, and then hermetically sealing theresin packaging bag by sealing the opening portion.

(17) A bag feeding type automatic filling method characterized bycomprising filling the resin packaging bag for a microwave ovendescribed in (6), which is to be used with a peripheral edge portionsealed and is obtained by covering a resin sheet with one resin filmbent into a tubular shape, forming a back lining seal between both endportions of the resin film and forming an end seal on one side thereof,with moisture-containing contents through an opening portion of theresin packaging bag for a microwave oven, and then hermetically sealingthe resin packaging bag by sealing the opening portion.

(18) A roll feeding type automatic filling method characterized bycomprising, for filling the resin packaging bag for a microwave ovendescribed in (7) with moisture-containing contents, feeding a resinsheet, or a resin sheet having a resin film adhered to a surface thereofthat is to form an inner side of the packaging bag, from a roll,disposing moisture-containing contents on the resin sheet, overlaying aresin film fed from another roll so as to cover the contents, sealingrespective side surface portions and then hermetically packaging byforming end seals at opening portions in two locations for each unitregion in which the contents are disposed, and then cutting outindividual pieces using a cutter.

(19) A packaged body obtained by filling the resin packaging bag for amicrowave oven described in any of (1) to (13) with moisture-containingcontents and hermetically sealing the resin packaging bag for amicrowave oven.

Advantageous Effects of Invention

The packaging bag according to the present invention can be heated in amicrowave oven in order to heat and cook the contents thereof, and theresin sheet can be deformed into a vessel shape and used as a foodvessel.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view showing the state of a packaged body prior to heating,the packaged body being obtained by filling a packaging bag according toa first embodiment of the present invention with contents andhermetically sealing the packaging bag;

FIG. 2 is a view showing a state in which the packaged body of FIG. 1has been heated in a microwave oven, causing a resin sheet to deforminto a recessed shape;

FIG. 3 is a view showing the state of a packaged body prior to heating,the packaged body being obtained by filling a packaging bag according toa second embodiment of the present invention with contents andhermetically sealing the packaging bag;

FIG. 4 is a view showing a state in which the packaged body of FIG. 3has been heated in a microwave oven, causing a resin sheet to deforminto a recessed shape;

FIG. 5 is a view showing the state of a packaged body prior to heating,the packaged body being obtained by filling a packaging bag according toa third embodiment of the present invention with contents andhermetically sealing the packaging bag;

FIG. 6 is a view showing a state in which the packaged body of FIG. 5has been heated in a microwave oven, causing a resin sheet to deforminto a recessed shape and then separate from a resin film;

FIG. 7 is a view showing the state of a packaged body prior to heating,the packaged body being obtained by filling a packaging bag according toa fourth embodiment of the present invention with contents andhermetically sealing the packaging bag;

FIG. 8 is a view showing a state in which the packaged body of FIG. 7has been heated in a microwave oven, causing a resin sheet to deforminto a recessed shape;

FIG. 9 is a view showing a configuration of a resin sheet of a packagingbag according to a fifth embodiment of the present invention;

FIG. 10 is a view showing an example of a frame sandwiching a peripheraledge portion of a packaging bag, the frame being used in a seventhembodiment of the present invention;

FIG. 11 is a view showing an example of a frame sandwiching a peripheraledge portion of a packaging bag, the frame being used in an eighthembodiment of the present invention;

FIG. 12 is a view showing another example of the frame sandwiching theperipheral edge portion of the packaging bag in the seventh embodimentof the present invention;

FIG. 13 is a view showing an automatic filling device used tomanufacture the packaging bags according to the first, second, third,and sixth embodiments of the present invention;

FIG. 14 is a view showing cross-sections taken along a-a′, b-b′, andc-c′ lines in FIG. 13; and

FIG. 15 is a view showing an example of a slit provided in the resinsheet.

MODE FOR CARRYING OUT THE INVENTION

A packaging bag according to the present invention functions as a simplevessel when a thin resin sheet provided on a bottom side of the bag isdeformed into a recessed shape by heat and pressure from the steamgenerated when the packaging bag is heated in a microwave oven, and cantherefore be of service to society as a disposable vessel that is highlyconvenient, reasonable-priced, and resource-friendly.

Furthermore, the present invention is groundbreaking in being applicableto any one of distribution at room temperature, distribution in arefrigerated state, and distribution in a frozen state.

Embodiments of the packaging bag according to the present invention willbe described below.

In the following description, a resin packaging bag for a microwave ovenaccording to the present invention will be referred to simply as a“packaging bag”.

First Embodiment

This embodiment is shown in FIGS. 1 and 2.

The packaging bag according to this embodiment is used with a peripheraledge portion sealed. A front side of the packaging bag is formed fromone resin film, and a rear side is formed from one resin sheet. Theresin film and the resin sheet comprise materials that, when a packagedbody obtained by hermetically sealing moisture-containing contentsbetween the resin film and the resin sheet is heated in a microwave ovenwith the rear side resin sheet as a bottom surface, are deformed by theheat and pressure of the steam generated from the contents such that therear side resin sheet forms a recessed shape, and this recessed shape isentirely or partially maintained even after heating is terminated.

The resin sheet may be a resin laminated sheet formed by adhering aresin film to at least a rear side surface thereof. As will be describedbelow, a slit may be provided in the resin sheet to facilitatedeformation thereof. When the resin sheet is formed from a resin havinga barrier property such that the barrier property is maintained over theentire packaging bag, the slit may damage the resin sheet, therebyimpairing the barrier property. By adhering a barrier resin film to therear side of the resin sheet, the barrier property of the packaging bagcan be maintained more reliably.

FIG. 1 shows an example of the packaging bag according to thisembodiment.

FIG. 1(A) is a view showing the packaged body in a state where thepackaging bag according to this embodiment has been filled with thecontents and hermetically sealed. FIG. 1(B) is a sectional view takenalong an a-a′ line in FIG. 1(A). FIG. 1(C) is an enlarged view showing across-section of a side seal portion 11 shown in FIG. 1(B).

The packaged body shown in FIG. 1(A) can be obtained by overlaying aresin film 2 onto a resin sheet 1 such that side seal portions 11, 12and an end seal portion 13 (a bottom seal) are formed, as shown in FIGS.1(B) and 1(C), thereby forming a three-way sealed bag, filling thethree-way sealed bag with moisture-containing contents 10 through anopening portion, and then forming an end seal (a top seal) portion 14 atthe opening portion.

The packaged body shown in FIG. 1(A) can also be obtained by placing themoisture-containing contents 10 on the resin sheet 1, overlaying theresin film 2 thereon, forming the side seal portions 11, 12, and thenvacuum-sealing the end seal portions 13, 14.

As shown in FIG. 1(C), a thermally welding layer 22 constituted by athermally weldable resin is provided on one surface of a base material21 of the resin film in order to form the seals.

When the packaged body shown in FIG. 1 is heated in a microwave oven,steam is generated from the moisture-containing contents 10, leading toan increase in an internal pressure of the packaged body, and as aresult, an interior volume of the packaging bag increases, as shown inFIG. 2. As the interior volume increases, stress is applied such that aperipheral edge portion of the resin film 2 pulls a peripheral edgeportion of the resin sheet 1 upward, and as a result, the resin sheet 1undergoes plastic deformation into a recessed shape so as to formavessel. When heating in the microwave oven is terminated, thetemperature and pressure of the heating steam no longer satisfy plasticdeformation conditions, and therefore the resin sheet 1 of the packagedbody remains in the recessed shape (the vessel shape).

FIG. 2 is a view showing a state in which the packaged body of FIG. 1has been heated in a microwave oven, causing the resin sheet to deforminto a recessed shape.

The resin film is then removed entirely or partially, and as a result,the recessed resin sheet can be used as is as a vessel.

A material that can be plastically deformed by applying stress theretoduring heating may be used as the material of the resin sheet 1, and asheet formed from polypropylene containing a filler may be cited as apreferred material. In this case, a thickness of approximately 200 to300 μm is sufficient as a thickness of the resin sheet.

The resin sheet 1 used in the present invention also includes a resinfoam sheet.

Meanwhile, a heat-resistant film that does not thermally contract evenwhen heated in a microwave oven is preferably used as the material ofthe resin film, and a polyethylene terephthalate film may be cited as anexample thereof. Further, the thermally weldable resin layer is providedon the thermally welding surface (surface to be welded) of the resinfilm to provide the resin film with a thermally welding property, andLLDPE (Linear Low Density Polyethylene) or CPP (Cast Polypropylene) ispreferably used as the thermally weldable resin.

Second Embodiment

This embodiment is shown in FIGS. 3 and 4. FIG. 3 shows an example of apackaged body obtained by filling a packaging bag according to thisembodiment with contents.

The packaging bag according to this embodiment is used with a peripheraledge portion sealed. As shown in FIG. 3(C), a front side of thepackaging bag is formed from two resin films 2, 3, and a rear side isformed from one resin sheet 1. Of the two resin films, the inside resinfilm 3 is adhered to the resin sheet 1, and the resin films 2, 3 and theresin sheet 1 comprise materials that, when a packaged body obtained bysealing moisture-containing contents between the two resin films isheated in a microwave oven with the rear side resin sheet 1 as thebottom surface, are deformed by the heat and pressure of the steamgenerated from the contents such that the rear side resin sheet 1 formsa recessed shape, and this recessed shape is entirely or partiallymaintained even after the heating is terminated.

FIG. 3(A) is a view showing the packaged body in a state where thepackaging bag according to this embodiment has been filled with thecontents and hermetically sealed. FIG. 3(B) is a sectional view takenalong a b-b′ line in FIG. 3(A). FIG. 3(C) is an enlarged view showing across-section of the side seal portion 11 shown in FIG. 3(B).

The packaged body shown in FIG. 3(A) is constituted by the resin film 2,the resin film 3, and the resin sheet 1, and is obtained by, forexample, forming a three-way sealed bag from the resin film 2 and theresin film 3, adhering the resin film 3 to the resin sheet 1, fillingthe three-way sealed bag with the moisture-containing contents 10through an opening portion, and then forming the end seal portion 14 atthe opening portion.

As shown in FIG. 3(C), thermally welding layers 22, 32 constituted by athermally weldable resin are provided on one surface of each of basematerials 21, 31 of the resin films in order to form the seals.

In this embodiment, the surface of the resin sheet 1 is overlaid ontothe surface of the resin film 3 on which the thermally welding layer isnot formed. When polypropylene containing a filler is used as the resinsheet 1 and a polyethylene terephthalate film is used as the resin film3, the two components cannot be adhered by a heat seal, and therefore anadhesion layer must be provided between the resin sheet 1 and the resinfilm 3.

FIG. 4 is a view showing a state in which the packaged body of FIG. 3has been heated in a microwave oven, causing the resin sheet 1 to deforminto a recessed shape.

Third Embodiment

This embodiment is shown in FIGS. 5 and 6. FIG. 5 shows an example of apackaged body obtained by filling a packaging bag according to thisembodiment with contents.

This embodiment is an application of the second embodiment.

In this embodiment, the adhesive layer provided between the resin sheet1 and the resin film 3 in the second embodiment is weakly adhesive.

Hence, after heating in the microwave oven is terminated, the resinsheet 1 can be separated from the resin films 2, 3 housing the contents10. The contents 10 housed in the resin films 2, 3 can then be takenout, transferred to the vessel formed by the resin sheet 1, and eaten.

The packaging bag according to this embodiment is similar to thepackaging bag according to the second embodiment in that the contentsare housed in the resin films 2, 3, and therefore the packaging bag canbe maintained in a hermetically sealed state even when a pinhole existsin the resin sheet 1.

FIG. 5(A) is a view showing the packaged body in a state where thepackaging bag according to this embodiment has been filled with thecontents and hermetically sealed. FIG. 5(B) is a sectional view takenalong a c-c′ line in FIG. 5(A). FIG. 5(C) is an enlarged view showing across-section of the side seal portion 11 shown in FIG. 5(B).

The packaged body shown in FIG. 5(A) is constituted by the resin film 2,the resin film 3, and the resin sheet 1. The packaged body is obtainedby, for example, forming a three-way sealed bag from the resin film 2and the resin film 3, adhering the resin film 3 to the resin sheet 1,filling the three-way sealed bag with the moisture-containing contents10 through the opening portion, and then forming the end seal portion 14at the opening portion.

As shown in FIG. 5(C), the thermally welding layers 22, 32 constitutedby thermally weldable resin are provided on one surface of each of thebase materials 21, 31 of the resin films in order to form a heat seal.

The adhesive layer between the resin sheet 1 and the resin film 3 isweakly adhesive, and therefore, when the packaging bag is heated in amicrowave oven, either adhered parts S of the resin sheet 1 and theresin film 3 separate from each other during heating or the resin sheet1 and the resin film 3 can be separated by applying force using thefingers once heating is completed.

FIG. 6 is a view showing a state in which the packaged body of FIG. 5has been heated in a microwave oven, causing the resin sheet 1 to deforminto a recessed shape.

Fourth Embodiment

This embodiment is shown in FIGS. 7 and 8.

The packaging bag according to this embodiment is used with a peripheraledge portion sealed. A front side and a rear side of the packaging bagare each formed from a resin film 2, and a resin sheet 1 is covered bythe front side resin film 2 and the rear side resin film 2. The resinfilm 2 and the resin sheet 1 comprise materials that, when a packagedbody obtained by sealing moisture-containing contents 10 between thefront side resin film 2 and the resin sheet 1 is heated in a microwaveoven with the rear side resin film 2 as the bottom surface, are deformedby the heat and pressure of the steam generated from the contents 10such that the rear side resin sheet 1 forms a recessed shape, and thisrecessed shape is entirely or partially maintained even after theheating is terminated.

Note that in this embodiment, the resin sheet 1 may be sandwichedbetween two resin films 2 such that a three-way seal is formed, or oneresin film 2 may be bent into a tubular shape, whereupon the resin sheet1 is disposed therein and a back lining seal is formed between both endportions of the resin film 2.

FIG. 7 shows an example of the packaging bag according to thisembodiment.

FIG. 7(A) is a view showing the packaged body in a state where thepackaging bag according to this embodiment has been filled with thecontents and hermetically sealed. FIG. 7 (B) is a sectional view takenalong a d-d′ line in FIG. 7(A). FIG. 7 (C) is an enlarged view showing across-section of the side seal portion 11 shown in FIG. 7(B).

In the packaged body shown in FIG. 7(A), the resin sheet 1 is covered bythe one resin film 2, and a back lining seal is formed between both endportions of the resin film 2 such that a back lining seal portion 15 isformed. Further, the front side resin film 2 and the resin sheet 1 aresealed at the peripheral edge portion.

The packaging bag according to this embodiment is advantaged in having asimple structure.

FIG. 8 is a view showing a state in which the packaged body of FIG. 7has been heated in a microwave oven, causing the resin sheet 1 to deforminto a recessed shape.

Fifth Embodiment

This embodiment is shown in FIG. 9.

In the packaging bag according to this embodiment, respectivepluralities of annular projecting portions 33 and annular recessedportions 34 are formed concentrically and alternately in advance on theresin sheet 1.

Various shapes, such as a rectangular ring shape, a circular ring shape,or an elliptical ring shape, may be selected as the annular shape.

In the example shown in FIG. 9, rectangular ring-shaped projectingportions and recessed portions are formed.

FIG. 9A is a view showing the packaging bag from the resin sheet 1 side,and FIG. 9B is a sectional view taken along an X-X line in FIG. 9A. Asshown in FIG. 9B, the resin sheet 1 is bent so as to have a wave-formsectional shape.

In the packaging bag according to the present invention, in which therear side resin sheet is to be deformed into a recessed shape by beingheated in a microwave oven, respective pluralities of annular projectingportions and annular recessed portions are formed alternately andconcentrically in a substantially planar resin sheet that is to bedeformed into the intended recessed shape by pressure.

The packaging bag according to this embodiment is formed bymanufacturing the concentric projections and recessions in advance inthe resin sheet through sheet molding using a die, overlaying the resinfilm onto the front side of the resin sheet, and then sealing them atthe peripheral edge portions thereof.

When a packaged body obtained by hermetically sealingmoisture-containing contents in this packaging bag is heated in amicrowave oven with the rear side resin sheet 1 as the bottom surface,the resin sheet 1 is softened by the heat and pressure of the steamgenerated from the contents. As the internal pressure increases, theannular projecting portions 33 and annular recessed portions 34, whichserve as an expansion allowance, expand such that the resin sheet 1 isformed into the shape of a vessel.

According to this embodiment, the recessed vessel shape generated byheating the packaging bag in a microwave oven can be formed more closelyto the intended shape than when the flat resin sheet 1 is used on thebottom surface side of the packaging bag.

FIG. 9 shows an example in which the concentric annular projectingportions 33 and annular recessed portions 34 are not provided at aperipheral portion of the resin sheet 1. However, a region of the resinsheet 1 in which the annular projecting portions 33 and annular recessedportions 34 are formed may be set as appropriate. The annular projectingportions 33 and annular recessed portions 34 may be provided over theentire surface of the resin sheet 1.

Sixth Embodiment

Examples of cases in which a three-way sealed bag is manufactured inadvance as the packaging bag and then filled with the contents weredescribed above.

As shown in FIG. 13, however, individual packaging bags may be formed byfeeding an elongated resin sheet 1, or a resin sheet 1 to which a resinfilm is adhered, and an elongated resin film 2 from respective rawmaterial rolls, disposing contents 10 between the resin sheet 1 and theresin film 2, forming a four-way seal in each unit region in which thecontents 10 are disposed, and then cutting out individual pieces using acutter 36. In this case, the packaged body is formed simultaneously withthe formation of the packaging bag. Nevertheless, this embodiment isalso included in the embodiments of the packaging bag according to thepresent invention.

Normally, the term “packaging bag” indicates a component having anopening before being filled with the contents. When the packaged body isformed simultaneously with the formation of the packaging bag using amethod such as that described above, however, the packaging bag is notprovided in a packaging bag form having an opening. Nevertheless, thepackaged body obtained using this method is in the state in which thepackaging bag is filled with the contents and then hermetically sealed,and it is therefore not different from a packaged body obtained byfilling a packaging bag having an opening with the contents and thenhermetically sealing the packaging bag.

Therefore, a packaging material part obtained in a case where thepackaged body is formed simultaneously with the formation of thepackaging bag, as described above, is likewise referred to in thepresent invention as the “packaging bag”.

This embodiment may be applied to the packaging bags of the first,second, and third embodiments.

Further, the annular projecting portions 33 and annular recessedportions 34 of the fifth embodiment, described above, may be formed inthe resin sheet after the resin sheet is fed from the raw material roll,and then the resin sheet may be conveyed to a content filling step.

In the case where feeding the packaging materials from the raw materialrolls, filling with the contents, and cutting into individual pieces areperformed in a single facility, as described above, the packaging bagsdo not have to be stocked, and therefore a large space saving effect canbe achieved.

(Other Embodiments of Packaging Bag)

The following may be mentioned as other embodiments relating to thepackaging bag.

(1) Slits may be provided in the resin sheet. When slits are provided inthis manner, the resin sheet deforms more easily. Needless to mention,the slits must be formed such that the packaging bag is maintained in ahermetically sealed state.

Slits 39 shown in FIG. 15, for example, may be formed as the slits toensure that the resin sheet can deform in accordance with the amount andshape of the contents.

(2) The resin sheet is basically planar in shape, but does notnecessarily have to be planar.

For example, a shallow recessed portion may be formed in the resin sheetin advance using a method such as embossing the resin sheet underapplication of heat thereto.

In so doing, the resin sheet can deform into the recessed shape easilywhen heated in a microwave oven. Note that when a deep recessed portionis formed, the packaged bag becomes bulky, leading to an increase indistribution cost. Moreover, the headspace increases, causing thepackaging bag to deform during vacuum-sealing. Hence, a deep recessedportion is not desirable.

(3) A gore such as a gusset may be provided on the resin film. Byproviding a gore, an interior volume of the bag can be increased inresponse to an increase in the amount of contents, making it unnecessaryto modify the type of resin bag in accordance with variation in the typeand amount of the contents.

(4) The packaging bag may be configured such that when the packaging bagis heated in a microwave oven, a steam vent opens automatically in apart of the resin film.

Depending on the heating time and the wattage of the microwave oven, thepackaging bag may rupture while being heated. To avoid this situation,means by which a steam vent opens automatically in a part of the resinfilm while the packaging bag is heated in the microwave oven may beprovided on the surface of the resin film. A configuration described inJapanese Patent No. 4817583 may be cited as an example of aconfiguration employed for this purpose.

(5) In a packaging bag in which the resin film is sealed at theperipheral edge portion of the resin sheet, a weak seal portion isprovided in a part of the seal portion. As a result, the weak sealportion peels away so as to open as a steam vent while the packaging bagis heated in the microwave oven, and therefore the packaged body doesnot rupture even when heated to excess.

Next, embodiments of a method of heating the packaging bag according tothe present invention in a microwave oven will be described.

Seventh Embodiment

This embodiment will be described on the basis of FIG. 10.

FIG. 10(A) is a view showing a frame 40 used when heating a packagedbody obtained by filling the packaging bag according to the presentinvention with contents, and FIGS. 10(B) to 10(D) show variation overtime in the state of the packaged body when the packaged body is heatedin a microwave oven while the peripheral edge portion of the packagingbag is sandwiched by the frame.

First, the frame 40 is prepared by connecting two frame members 41, 42shown in FIG. 10(A) via a hinge 43. Next, as shown in FIG. 10(B), aflange portion (the peripheral edge portion) 46 of the packaging bag issandwiched between the frame members 41, 42 and fixed by fixing members44, 45 so that the flange portion 46 does not deviate from the frame 40.

When the packaged body is heated in a microwave oven in this state, thepackaging bag expands such that the resin sheet deforms plastically intoa vessel shape, as shown in FIG. 10C. After heating in the microwaveoven is completed, the resin sheet remains in the vessel shape, as shownin FIG. 10(D).

When the frame 40 is used in this manner, the flange portion 46 of theresin sheet is restrained by the frame so as to remain in a planarstate. Hence, the flange portion does not become ruffled, and as aresult, a vessel having an aesthetically pleasing appearance isobtained.

Eighth Embodiment

This embodiment will be described on the basis of FIG. 11. FIG. 11(A) isa view showing a frame 50 having a wall surface, which is used whenheating a packaged body obtained by filling the packaging bag accordingto the present invention with contents, and FIGS. 11(B) to 11(D) showvariation over time in the state of the packaged body when the packagedbody is heated in a microwave oven while the peripheral edge portion ofthe packaging bag is sandwiched by the frame.

First, the frame 50 is prepared by connecting a frame member 51 having awall surface such as that shown in FIG. 11(A) and a frame member 52 viaa hinge 53. Next, as shown in FIG. 11(B), the flange portion (theperipheral edge portion) 46 of the packaging bag is sandwiched betweenthe frame members 51, 52 and fixed by fixing members 54, 55 so that theflange portion 46 does not deviate from the frame.

When the packaged body is heated in a microwave oven in this state, thepackaging bag expands such that the resin sheet deforms plastically intoa vessel shape, as shown in FIG. 11 (C). After heating in the microwaveoven is complete, the resin sheet remains in the vessel shape, as shownin FIG. 11 (D).

Further, the wall surface 51 does not have to be formed entirely from awall material, and cavity portions 56 may be provided in the wallsurface, as shown in FIG. 12.

When the frame 50 is used in this manner, plastic deformation of thepart of the resin sheet that forms the vessel can be controlled so thatthe resin sheet is brought to the conditions like being die-molded inthe microwave oven. Hence, the resin sheet can be molded into a vesselhaving an intended shape, and as a result, an aesthetically pleasingappearance more closely resembling a vessel can be obtained.

Embodiments of a method of filling the packaging bag according to thepresent invention will now be described.

Ninth Embodiment

When the packaging bag according to the above embodiments is a resinpackaging bag formed by sealing the peripheral edge portion at threesides, automatic filling is performed by filling the packaging bag,which is conveyed to an automatic filling device, withmoisture-containing contents through an unsealed opening portion, andthen hermetically sealing the packaging bag by sealing the openingportion (bag feeding type automatic filling method).

Tenth Embodiment

When the packaging bag is the resin packaging bag according to thefourth embodiment, automatic filling is performed by covering a resinsheet with a resin film bent into a tubular shape, forming a back liningseal on the resin film and an end seal on one side of the packaging bag,filling the packaging bag with moisture-containing contents through theopening portion, and then hermetically sealing the packaging bag bysealing the opening portion (bag feeding type automatic filling method).

Eleventh Embodiment

When the packaging bag is the resin packaging bag according to the firstembodiment, automatic filling is performed by feeding a resin sheet froma roll, disposing moisture-containing contents on the resin sheet,overlaying a resin film, which is fed from a roll, so as to cover thecontents, sealing the side surface portions and then hermeticallypackaging by forming end seals at the two opening portions for each unitregion in which the contents are disposed, and then cutting outindividual pieces using a cutter (a roll feeding type automatic fillingmethod).

FIG. 13 is a view illustrating the roll feeding type automatic fillingmethod according to this embodiment.

The resin sheet 1 fed from the raw material roll is conveyed toward avacuum sealing device 35.

The moisture-containing contents are placed on the resin sheet 1 as theresin sheet 1 is conveyed. FIG. 14A is a sectional view taken along ana-a′ line in FIG. 13.

Next, the resin film 2, which is fed from the other raw material roll,is overlaid onto the moisture-containing contents 10. FIG. 14B is asectional view taken along a b-b′ line in FIG. 13.

The resin sheet 1 and the moisture-containing contents 10 onto which theresin film 2 is overlaid enter the vacuum sealing device and undergovacuum degassing and sealing in the vacuum sealing device, therebyforming the sealed packaged bodies. FIG. 14C is a sectional view takenalong a c-c′ line in FIG. 13. As shown in FIG. 14C, the resin sheet 1,the resin film 2, and the moisture-containing contents 10 are in closecontact with each other.

Next, a continuous body of vacuum-sealed packaging bags is cut intoindividual pieces by the cutter 36, thereby forming packaged bodies 37.

In FIG. 13, a shaded part at the periphery of the packaged body 37indicates a seal portion 38.

Twelfth Embodiment

A packaged body that is obtained by housing moisture-containing contentsin the resin packaging bag for a microwave oven according to therespective embodiments described above and hermetically sealing thepackaging bag is also included in the embodiments of the presentinvention.

EXAMPLES

The present invention will now be described on the basis of examples.Note that a so-called person skilled in the art could easily conceive ofother embodiments by applying appropriate modifications and amendmentsto the examples of the present invention described below, and thesemodifications and amendments are included in the present invention. Thefollowing description illustrates examples of preferred embodiments ofthe present invention, and the present invention is not limited to theseexamples.

Note that in the following description, PET, LLDPE, and PP respectivelydenote polyethylene terephthalate, linear low density polyethylene, andpolypropylene.

Further, the resin film and the resin sheet used in the examples arerespectively configured as follows.

(Resin Film)

PET (thickness 12 μm): P60 Toray Industries, Inc.

LLDPE (thickness 50 μm): XHT Futamura Chemical Co., Ltd.

(Resin Sheet)

PP sheet (thickness 250 μm) containing filler (talc, calcium carbonate)

Example 1 Test Conditions

The packaging bag shown in FIG. 1 was manufactured as follows.

Size of sample (packaging bag): 128 mm×175 mm

Resin film: PET (thickness 12 μm)/LLDPE (thickness 50 μm)

Resin sheet: PP sheet (thickness 250 μm) containing filler

Bag shape: The resin film was directly sealed to the peripheral edge ofthe resin sheet.

Contents: Paper containing 10 cc of water

Heat setting of microwave oven: 500 W, 1 minute

Number of samples: 5

(Test Results)

As a result of heating in a microwave oven, the average value of theheights from the bottom surface of the resin sheet to the seal portionof the same at four sides was 31.75 mm.

Example 2

(Test Conditions)

The packaging bag shown in FIG. 3 was manufactured as follows.

Size of sample (packaging bag): 128 mm×175 mm

Resin film: PET (thickness 12 μm)/LLDPE (thickness 50 μm)

Resin sheet: PP sheet (thickness 250 μm) containing filler

Bag shape: A three-way sealed bag formed from the resin films wasadhered directly to the resin sheet.

Contents: Paper containing 10 cc of water

Heat setting of microwave oven: 500 W, 1 minute

Number of samples: 5

(Test Results)

As a result of heating in a microwave oven, the average value of theheights from the bottom surface of the resin sheet to the seal portionof the same at four sides was 29.25 mm.

Example 3

(Test Conditions)

The packaging bag shown in FIG. 5 was manufactured as follows.

Size of sample (packaging bag): 128 mm×175 mm

Resin film: PET (thickness 12 μm)/LLDPE (thickness 50 μm)

Resin sheet: PP sheet (thickness 250 μm) containing filler

Bag shape: A three-way sealed bag formed from the resin films wasadhered weakly to the resin sheet at a desired width on only four sides.

Contents: Paper containing 10 cc of water

Heat setting of microwave oven: 500 W, 1 minute

Number of samples: 5

(Test Results)

As a result of heating in a microwave oven, the average value of theheights from the bottom surface of the resin sheet to the seal portionof the same at four sides was 29.75 mm.

Moreover, it was possible to separate the resin sheet from the resinfilms easily after heating in the microwave oven.

Example 4

(Test conditions)

The packaging bag shown in FIG. 7 was manufactured as follows.

Size of sample (packaging bag): 128 mm×175 mm

Resin film: PET (thickness 12 μm)/LLDPE (thickness 50 μm)

Resin sheet: PP sheet (thickness 250 μm) containing filler

Bag shape: Four sides of an upper surface of the resin sheet were sealedto a butt-seam bag formed from the resin film with a desired width.

Contents: Paper containing 10 cc of water

Heat setting of microwave oven: 500 W, 1 minute

Number of samples: 5

(Test Results)

As a result of heating in a microwave oven, the average value of theheights from the bottom surface of the resin sheet to the seal portionof the same at four sides was 27.75 mm.

Example 5

(Test Conditions)

A packaging bag was manufactured in an identical manner to Example 4except that the resin sheet shown in FIG. 9 was used as the resin sheetin Example 4.

Size of sample (packaging bag): 128 mm×175 mm

Resin film: PET (thickness 12 μm)/LLDPE (thickness 50 μm)

Resin sheet: PP sheet (thickness 200 μm) containing filler

Number of annular projecting portions: 3 (H=3 mm, L=4 mm)

Bag shape: Four sides of the upper surface of the resin sheet weresealed to a butt-seam bag formed from the resin film with a desiredwidth.

Contents: Paper containing 10 cc of water

Heat setting of microwave oven: 500 W, 1 minute

Number of samples: 5

(Test Results)

In Examples 1 to 4, the average value of the heights from the bottomsurface of the resin sheet to the seal portion of the same at four sideswas 27.75 mm as a result of heating in a microwave oven.

In Example 5, the average value of the heights from the bottom surfaceof the resin sheet to the seal portion of the same at four sides was42.50 mm as a result of heating in a microwave oven.

The heated resin sheets obtained in the examples described above wereall formed into a bowl shape with a height of approximately 30 mm, andwere therefore deep enough to be used as food vessels.

Effects of the packaging bag according to the present invention are asfollows.

(1) The packaging bag according to the present invention enables heatingand cooking of the contents therein by being heated in a microwave, andthe resin sheet thereof can be deformed into the shape of a vessel andused as a food vessel.

(2) In the case of a packaging container employing a tray, the traydeforms when headspace exists and the packaging container isheat-sterilized after being vacuum-packed. Therefore, the packagingcontainer is not suitable for this packing/sterilization method. Withthe packaging bag according to the present invention, however, vacuumsterilization and packing can be performed.

(3) When a packaging container includes headspace, the container becomesbulky, leading to poor space efficiency (material storage spaceefficiency, transportation efficiency, display efficiency) on a foodpackaging site and during distribution. The packaging bag according tothe present invention, however, is not as bulky as a packagingcontainer, and therefore favorable space efficiency is achieved on thefood packaging site and during distribution.

(4) The resin sheet used in the present invention is thinner than aresin sheet used in a packaging container, and therefore an amount ofused resin material can be reduced, which is environmentally friendly.

(5) The packaging bag according to the present invention basically takesa planar shape with a facing surface formed from a resin film, andtherefore has excellent eye-catching effect and allows greater designfreedom than a packaging container constituted by a tray and a lidmaterial.

EXPLANATION OF REFERENCE SIGNS

-   1 resin sheet-   2 resin film-   3 resin film-   10 moisture-containing contents-   11, 12 side seal portion-   13, 14 end seal portion-   15 back lining seal portion-   21 resin film base material-   22 thermally welding layer-   31 resin film base material-   32 thermally welding layer-   33 projecting portion-   34 recessed portion-   35 vacuum sealing device-   36 cutter-   37 packaged body-   38 seal portion-   39 slit-   40 frame-   41, 42 frame member-   43 hinge-   44, 45 fixing member-   46 flange portion-   50 frame-   51, 52 frame member-   53 hinge-   54, 55 fixing member-   56 cavity portion-   S adhered part

1. A resin packaging bag for a microwave oven, which is used with aperipheral edge portion sealed, characterized in that: a front side ofthe packaging bag is formed from one resin film and a rear side isformed from one resin sheet; and the resin film and the resin sheetcomprise materials that, when a packaged body obtained by hermeticallysealing moisture-containing contents between the resin film and theresin sheet is heated in a microwave oven with the rear side resin sheetas a bottom surface, are deformed by heat and pressure of steamgenerated from the contents such that the rear side resin sheet forms arecessed shape, and the recessed shape is entirely or partiallymaintained even after heating is terminated.
 2. The resin packaging bagfor a microwave oven according to claim 1, characterized in that theresin sheet is a resin laminated sheet obtained by adhering a resin filmto a rear side surface thereof.
 3. A resin packaging bag for a microwaveoven, which is used with a peripheral edge portion sealed, characterizedin that: a front side of the packaging bag is formed from two resinfilms and a rear side is formed from one resin sheet; of the two resinfilms, a resin sheet-side resin film is adhered to a front side surfaceof the resin sheet; and the resin films and the resin sheet comprisematerials that, when a packaged body obtained by hermetically sealingmoisture-containing contents between the two resin films is heated in amicrowave oven with the rear side resin sheet as a bottom surface, aredeformed by heat and pressure of steam generated from the contents suchthat the rear side resin sheet forms a recessed shape, and the recessedshape is entirely or partially maintained even after heating isterminated.
 4. The resin packaging bag for a microwave oven according toclaim 3, characterized in that the resin sheet and the resin sheet-sideresin film are adhered weakly and the adhesive layer is weakly adhesiveso that when the packaging body is heated in the microwave oven, theresin films housing the contents can be separated from the resin sheet.5. (canceled)
 6. (canceled)
 7. The resin packaging bag for a microwaveoven according to claim 1, characterized in that the resin packaging bagfor a microwave oven is formed by disposing moisture-containing contentsbetween an elongated resin sheet, or an elongated resin sheet having aresin film adhered to a surface thereof that is to form an inner side ofthe packaging bag, and an elongated resin film, forming a four-way sealfor each unit region in which the contents are disposed, and cutting outindividual pieces using a cutter.
 8. The resin packaging bag for amicrowave oven according to claim 1, characterized in that a slit isinserted into the resin sheet.
 9. The resin packaging bag for amicrowave oven according to claim 1, characterized in that a shallowrecessed portion is formed in advance near a central portion of theresin sheet.
 10. The resin packaging bag for a microwave oven accordingto claim 1, characterized in that respective pluralities of annularrecessed portions and annular projecting portions are formedconcentrically and alternately in advance in the resin sheet. 11.(canceled)
 12. The resin packaging bag for a microwave oven according toclaim 1, characterized in that means by which a steam vent opensautomatically while heating in the microwave oven is provided on thesurface of the resin film.
 13. The resin packaging bag for a microwaveoven according to claim 1, characterized in that a part of a sealportion between the resin film and the resin sheet is formed from a weakseal so that the weak seal part peels away during heating in themicrowave oven, thereby opening as a steam vent. 14.-17. (canceled) 18.A roll feeding type automatic filling method characterized bycomprising, for filling the resin packaging bag for a microwave ovenaccording to claim 7 with moisture-containing contents, feeding a resinsheet, or a resin sheet having a resin film adhered to a surface thereofthat is to form an inner side of the packaging bag, from a roll,disposing moisture-containing contents on the resin sheet, overlaying aresin film fed from another roll so as to cover the contents, sealingrespective side surface portions and then hermetically packaging byforming end seals at opening portions in two locations for each unitregion in which the contents are disposed, and then cutting outindividual pieces using a cutter.
 19. A packaged body obtained byfilling the resin packaging bag for a microwave oven according to claim1 with moisture-containing contents and hermetically sealing the resinpackaging bag for a microwave oven.
 20. The resin packaging bag for amicrowave oven according to claim 3, characterized in that the resinpackaging bag for a microwave oven is formed by disposingmoisture-containing contents between an elongated resin sheet, or anelongated resin sheet having a resin film adhered to a surface thereofthat is to form an inner side of the packaging bag, and an elongatedresin film, forming a four-way seal for each unit region in which thecontents are disposed, and cutting our individual pieces using a cutter.21. The resin packaging bag for a microwave oven according to claim 3,characterized in that a slit is inserted into the resin sheet.
 22. Theresin packaging bag for a microwave oven according to claim 3,characterized in that a shallow recessed portion is formed in advancenear a central portion of the resin sheet.
 23. The resin packaging bagfor a microwave oven according to claim 7, characterized in that ashallow recessed portion is formed in advance near a central portion ofthe resin sheet.
 24. The resin packaging bag for a microwave ovenaccording to claim 20, characterized in that a shallow recessed portionis formed in advance near a central portion of the resin sheet.
 25. Theresin packaging bag for a microwave oven according to claim 3,characterized in that respective pluralities of annular recessedportions and annular projecting portions are formed concentrically andalternately in advance in the resin sheet.
 26. The resin packaging bagfor a microwave oven according to claim 7, characterized in thatrespective pluralities of annular recessed portions and annularprojecting portions are formed concentrically and alternately in advancein the resin sheet.
 27. The resin packaging bag for a microwave ovenaccording to claim 20, characterized in that respective pluralities ofannular recessed portions and annular projecting portions are formedconcentrically and alternately in advance in the resin sheet.
 28. A rollfeeding type automatic filling method characterized by comprising, forfilling the resin packaging bag for a microwave oven according to claim20 with moisture-containing contents, feeding a resin sheet, or a resinsheet having a resin film adhered to a surface thereof that is to forman inner side of the packaging bag, from a roll, disposingmoisture-containing contents on the resin sheet, overlaying a resin filmfed from another roll so as to cover the contents, sealing respectiveside surface portions and then hermetically packaging by forming endseals at opening portions in two locations for each unit region in whichthe contents are disposed, and then cutting out individual pieces usinga cutter.
 29. A packaged body obtained by filling the resin packagingbag for a microwave oven according to claim 3 with moisture-containingcontents and hermetically sealing the resin packaging bag for amicrowave oven.
 30. A packaged body obtained by filling the resinpackaging bag for a microwave oven according to claim 7 withmoisture-containing contents and hermetically sealing the resinpackaging bag for a microwave oven.
 31. A packaged body obtained byfilling the resin packaging bag for a microwave oven according to claim20 with moisture-containing contents and hermetically sealing the resinpackaging bag for a microwave oven.